The thermally conductive sheet is used for filling a gap between an electronic component, which is a heat source, and the like, and a heat sink, for example, a heat dissipation plate or a chassis to increase the heat dissipation performance of electronic component. As the thermally conductive sheet, a thermally conductive sheet having an adhesion property is preferred from the standpoint of workability in the case of assembling the electronic component and the heat sink using the thermally conductive sheet. Further, a thermally conductive sheet in which an adhesion property of one surface is high and an adhesion property of the other surface is low is preferred from the standpoint of reworkability, for example, to correct a position deviation at the time of assembling of the electronic component and the heat sink or to enable reassembling after once assembled and disassembled for any reason.
Thus, in the formation of thermally conductive sheet from a silicone rubber and a thermally conductive filler, it is proposed to apply a non-adhesive treatment to a surface of the sheet by ultraviolet ray irradiation (Patent Document 1).
Also, an adhesive thermally conductive sheet containing a non-functional acrylic polymer and a thermally conductive filler in an acrylic polyurethane resin, wherein a blend ratio of the acrylic polyurethane resin and the non-functional acrylic polymer is differentiated in a surface layer and a back layer and the both layers are coated superposedly to vary the adhesion property on the front side and the back side of adhesive thermally conductive sheet is proposed (Patent Document 2).